72 ANALYSIS OF THE SHOOT-SYSTEM OF FERNS [CH. 



the arrest of sori, as in the case of Cystopteris bidbifera. A good instance of 

 this has been noted in Woodivardia radicans (Fig. 6^), where buds are found 

 on the upper surface of the leaf, at points immediately above arrested sori. 

 Their formation is undoubtedly connected with the arrest, and the buds may 



Fig. 66. Cystopteris btdbifera (L.), Bernh. 

 ^ =part of a leaf with adventitious buds. 

 Natural size. B = a.n adventitious bud 

 which has fallen off, forming a root. 

 C=an adventitious bud further de- 

 veloped. B and C somewhat enlarged. 

 (After Matonschek.) 



Fig. 67. A pinna of IVoodivardia 

 radicans, showing many sporo- 

 phytic buds on the upper surface. 

 They correspond in position to 

 sori on the lower surface, which 

 are imperfectly developed. 



be held as an alternative method of using the material available for spore- 

 formation. The buds borne thus upon the lamina cannot be related to any 

 regular method of branching of the shoot, and their origin is held to be 

 adventitious. 



